The 31-year-old Once Upon a Time... In Hollywood star was showing off about her husband's brush with stardom on The Graham Norton Show, and revealed she'd have been even more into him if he'd told her of his appearance earlier.
Ackerley is a successful film producer in his own right, but Harry Potter mad Margot was gushing about his brief cameo in the third film, Harry Potter and the Prisoner of Azkaban.
Tom, who is also 31, appeared in a scene during with Malfoy - played by Tom Felton - shoved past several students to get to the hippogriff Buckbeak.
Of course, if you're not a Harry Potter fan, you might as well ignore that sentence, as it will make no sense whatsoever.
We can't confirm this for definite, but there's a good chance he was also in the first and second films, too.
In January 2020, speaking to host Graham, Robbie said: "My husband is in the Harry Potter movies. I know, I was like, 'Had you told me sooner we would've been married very quickly.'
"But he was an extra, when he was a little kid he was one of the Slytherin extras when Draco pushes some kids out of the way to see Buckbeak in the third book.
"He pushes my husband out of the way."
On the same show, Graham showed the audience a picture illustrating just how into Harry Potter she was, as she was pictured reading the fifth book, Harry Potter and the Order of the Phoenix, while sipping a cup of tea.
The Australian actor then revealed she was only wearing glasses because she wanted to be 'like Harry', and had lied to her optometrist to get them.
Margot and Tom met on the set of Suite Francaise back in 2013, and started dating in 2014.
They married in December 2016 and have been together ever since.
The pair have even worked together on a number of occasions, notably in 2017 on I, Tonya, in which Margot played disgraced ice-skater Tonya Harding.
They also worked together on the live action Barbie movie - in which Margot plays the titular toy alongside Ryan Gosling as Ken.
Tom has also worked on Netflix series Maid and Promising Young Woman.
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